Macular edema(ME) is a common cause of significant visual loss in a wide variety of ocular condition, including age-related macular degeneration (AMD) and diabetic retinopathy (DR). The early detection and classification of ME is of special importance in DR, since the optimum treatment depends on position, type, and extension of the ME. Our long term goal is to develop a clinically useful tool to map macula thickness, to screen for clinically significant macular edema, and to provide high resolution images of retinal cross-sections at any arbitrary retinal locations. In the proposed technique, the rapid transverse imaging mode of the scanning laser ophthalmoscope (SLO) will be combined with high depth resolution and sectioning capability of the optical coherence tomography (OCT). This instrument will be able to image the retina in three dimensions, delineate ME boundaries, and quantify ME volume. During Phase l of this study, we will focus our effort on proof of feasibility. We will modify a breadboard system based on a Topographic Scanning System TopSS(Laser Diagnostic Technologies, Inc.) perform in vivo measurements on a few normal subjects and a few ME patients, develop 3-D image processing software, and identify potential problems and improvements for Phase II work.